The killings triggered a police manhunt for the killer of Isabelle Brandon (60), a justice of the peace, and her clerk, Andre Bellemans. Officers are investigating a theory that the murderer is an Albanian defendant angry at a ruling by Ms Brandon in an earlier case heard "some days ago".

Danielle Bloeum, a court lawyer, said that Mrs Brandon had specialised in hearings for mentally ill people who faced court orders for compulsory treatment. "A justice of the peace has the right to put people in hospital. I am afraid that one of these people did this," she said.

According to witnesses, the gunman struck Mr Bellemans with a hatchet before taking careful aim to shoot Judge Brandon. Both were killed instantly.

He was then chased out of the Justice de Paix courts by a lawyer who lost sight of the killer, still carrying his pistol, as he fled into the maze of small streets that surrounds the court.

Police are still hunting the man after evacuating a nearby school and sealing off streets in the Marolles-Sablon district.

Stefaan De Clerck, Belgium's federal justice minister, said that there were no security checks for the courtroom for civil disputes between families or neighbours for settling small claims under the value of €1,861.